Resolver SwiftUI Causing Crash - What Order Do Things Get Called? - firebase

Question

I am working on SwiftUI and using Resolver for Dependency Injection. As a backend I am using Firebase. I've created an AuthSession file that handles all of my user authentication stuff. In the project I also have a number of other repositories that populate data throughout the app. In AuthSession I am creating properties for each repository so that I can start and stop Firestore Listeners on login and logout. In a couple of these repositories I want to access AuthSession through #InjectedObject so that when a user logs in I can be notified and can get updates via Combine. My issues is that when I start the app, it crashes with an odd Firebase error.
AuthSession.swift
class AuthSession: ObservableObject {
let db = Firestore.firestore()
var offerRepository: OfferRepository = Resolver.resolve()
var handle: AuthStateDidChangeListenerHandle?
#Published var currentUser: User?
#Published var loggedIn = false
#Published var currentUserUid = ""
// Combine Cancellable
private var cancellables = Set<AnyCancellable>()
// Intitalizer
init() {
}
func listen() {
print("AuthSession - listen called")
// Monitor Authentication chagnes using Firebase Auth.
handle = Auth.auth().addStateDidChangeListener{ (auth, user) in
// Check to see if a user is returned from a sign in or sign up event.
if let user = user {
// Set loggedIn to true. This will also be set when a new User is created in SignUpView.
print("User Exists.")
self.loggedIn = true
self.currentUserUid = user.uid
self.currentUser = user
} else {
print("Not logged in")
}
}
}
}
Below is OfferRepository. When the line below is added it crashes. If the line is removed it does not crash. I'm not sure why. The Combine code is not included.
Line causing the crash.
#InjectedObject var authSession: AuthSession
OfferRepository.swift
class OfferRepository: ObservableObject {
let db = Firestore.firestore()
private var snapshotListener: ListenerRegistration?
#InjectedObject var authSession: AuthSession
#Published var offers = [Offer]()
private var cancellables = Set<AnyCancellable>()
init() {
startSnapshotListener()
}
func startSnapshotListener() {
if snapshotListener == nil {
self.snapshotListener = db.collection(FirestoreCollection.offers).order(by: "created", descending: true).addSnapshotListener { (querySnapshot, error) in
if let error = error {
print("Error getting documents: \(error)")
} else {
guard let documents = querySnapshot?.documents else {
print("No Offers.")
return
}
self.offers = documents.compactMap { offer in
do {
return try offer.data(as: Offer.self)
} catch {
print(error)
}
return nil
}
}
}
}
}
}
For reference here is my AppDelegate+Registering file.
extension Resolver: ResolverRegistering {
public static func registerAllServices() {
register { AuthSession() }.scope(.application)
register { OfferRepository() as OfferRepository }.scope(.application)
}
}
The app crashed on the line below from the Firestore package.
- (NSString *)keyForDatabase:(NSString *)database {
return [NSString stringWithFormat:#"%#|%#", self.app.name, database];
}
Thread 1: EXC_BAD_ACCESS (code=2, address=0x16d317ff8)
While I can start and stop listeners from login and logout views, I'd prefer to keep this in the AuthSession file. Is there a way around this?

Answer 1

#InjectedObject is intended to be used to inject ObservableObjects into SwiftUI views - see the docs: https://github.com/hmlongco/Resolver#property-wrappers
As you want to reference the AuthenticationService inside your repositories (which are ObservableObjects, you should use #Injected instead.
Here is a snippet from one of my apps:
public class ArtifactRepository: ObservableObject {
// MARK: - Dependencies
#Injected var db: Firestore
#Injected var authenticationService: AuthenticationService
// MARK: - Publishers
#Published public var artifacts = [Artifact]()
// MARK: - Private attributes
private var statusFilter: Status
private var userId: String = "unknown"
private var listenerRegistration: ListenerRegistration?
private var cancellables = Set<AnyCancellable>()
let logger = Logger(subsystem: "dev.peterfriese.App", category: "persistence")
public init(statusFilter: Status = .inbox, liveSync: Bool = true) {
// filtering
self.statusFilter = statusFilter
// observe user ID
authenticationService.$user
.compactMap { user in
user?.uid
}
.assign(to: \.userId, on: self)
.store(in: &cancellables)
// if live sync is on, (re)load data when user changes
if liveSync {
authenticationService.$user
.receive(on: DispatchQueue.main)
.sink { [weak self] user in
if self?.listenerRegistration != nil {
self?.unsubscribe()
self?.subscribe()
}
}
.store(in: &cancellables)
}
}
deinit {
unsubscribe()
}
public func unsubscribe() {
if listenerRegistration != nil {
listenerRegistration?.remove()
listenerRegistration = nil
}
}
public func subscribe() {
if listenerRegistration == nil {
var query = db.collection("artifacts")
.whereField("userId", isEqualTo: self.userId)
if (statusFilter != .all) {
query = query.whereField("status", isEqualTo: statusFilter.rawValue)
}
listenerRegistration = query.order(by: "dateAdded", descending: true)
.addSnapshotListener { [weak self] (querySnapshot, error) in
guard let documents = querySnapshot?.documents else {
self?.logger.debug("No documents")
return
}
self?.logger.debug("Mapping \(documents.count) documents")
self?.artifacts = documents.compactMap { queryDocumentSnapshot in
try? queryDocumentSnapshot.data(as: Artifact.self)
}
}
}
}
}
public class AuthenticationService: ObservableObject {
private let logger = Logger(subsystem: "dev.peterfriese.App", category: "authentication")
#Published public var user: User?
private var handle: AuthStateDidChangeListenerHandle?
public init() {
setupKeychainSharing()
registerStateListener()
}
public func signIn() {
if Auth.auth().currentUser == nil {
Auth.auth().signInAnonymously()
}
}
public func signOut() {
do {
try Auth.auth().signOut()
}
catch {
print("error when trying to sign out: \(error.localizedDescription)")
}
}
private let accessGroup = "XXXXXXX.dev.peterfriese.App"
private func setupKeychainSharing() {
do {
let auth = Auth.auth()
auth.shareAuthStateAcrossDevices = true
try auth.useUserAccessGroup(accessGroup)
}
catch let error as NSError {
print("Error changing user access group: %#", error)
}
}
private func registerStateListener() {
if handle == nil {
handle = Auth.auth().addStateDidChangeListener({ (auth, user) in
self.user = user
if let user = user {
if user.isAnonymous {
self.logger.debug("User signed in anonymously with user ID \(user.uid).")
}
else {
self.logger.debug("User signed in with user ID \(user.uid). Email: \(user.email ?? "(empty)"), display name: [\(user.displayName ?? "(empty)")]")
}
}
else {
self.logger.debug("User signed out.")
self.signIn()
}
})
}
}
}